The present invention relates to liquid or pasty compositions which contain in particular difluoromethoxy-2,2,2-trifluoroethane (E245) as solvent and at least one agent having release-effective properties, and also to the use of these compositions and a method for their preparation.
In many industrial fields of use which include operating processes such as casting, molding, pressing, etc. (e.g. for the production and processing of plastics, foamed materials, building materials, rubber articles, tires, metals, glass, ceramic products etc.), it is now required that release agents, lubricants or parting agents be used. As used herein, the term "release agent" refers to a solid or liquid film which reduces the adhesive forces between two adjoining surfaces, i.e. which prevents the surfaces from adhering to each other. The term "lubricant" refers to an additive for plastic compounds, e.g. compression-molding compounds and injection-molding compounds. Lubricant additives are required to make the fillers slide more easily and thus to make the compression-molding compounds easier to deform. The release agents, lubricants or parting agents contain release-effective constituents, e.g. in the form of dry powders, dry films or wet films, pastes, burned-in films, solutions or dispersions. One special form is represented by the so-called internal release-effective components which are mixed into the material which is to be demolded and are either capable of concentrating at the surface of the molded article or which bring about more rapid hardening of the surface, so that there is no bond between the mold wall and the molded article.
Not infrequently in operating processes of the foregoing type, residues of the agent having release-effective properties must be removed from time to time from the mold with the aid of solvents. Typically, solvents such as hydrocarbons and chlorohydrocarbons have been used to clean the molds. However, hydrocarbon solvents are a fire hazard, and chlorohydrocarbon solvents cause skin irritations.
U.S. Pat. No. 4,028,120 discloses a mold release agent for the production of molded rubber products and the shaping of polyurethane foam material. The mold release compound used therein contains paraffin wax, lamp oil and sodium soaps of tall oil acids in a paraffinic base oil. The mold release agent used must be soluble or emulsifiable in water, in order to be able to separate the mold release agent from the molded product by spraying or washing with hot water.
Furthermore, mold release agents are known which contain fluorochlorocarbons as the primary solvent or dispersing agent. For instance, U.S. Pat. No. 4,995,908 describes release agent compositions with 1,1-dichloro2,2,2-trifluoroethane (R123); U.S. Pat. No. 5,087,285 describes release agent compositions with 1,1-dichloro-1fluoroethane, and published German patent application No. DE-OS 4,006,688 discloses release agent compositions with dichloropentafluoropropanes (R225). Despite these many diverse formulations, there is still a need in the art to discover beneficial alternatives suitable for use as release agent compositions.